Let's do some math ..  Rounding examples of 7 random hypothetical purchases:
Case	Tag   Price	Sales   Tax %	Raw Total   Incl. Sales Tax	Rounded   to Penny	Rounded   to Nickel	Rounded   to Dime
Purchase #1	$42.47	3.871%	$44.114	$44.11	$44.10	$44.10
Purchase #2	$182.86	4.179%	$190.5017	$190.50	$190.50	$190.50
Purchase #3	$73.42	6.525%	$78.2107	$78.21	$78.20	$78.20
Purchase #4	$166.38	9.815%	$182.7102	$182.71	$182.70	$182.70
Purchase #5	$83.74	13.450%	$95.003	$95.00	$95.00	$95.00
Purchase #6	$184.38	8.804%	$200.6128	$200.61	$200.60	$200.60
Purchase #7	$218.63	7.571%	$235.1825	$235.18	$235.20	$235.20
7 purchase totals =	$951.88		$1,026.3349	$1,026.32	$1,026.30	$1,026.30